Online monitoring of Aeromonas in drinking-water distribution system without chlorine

The microbiological analyses currently used to monitor drinking-water quality are relatively time-consuming and they cannot be used for continuous monitoring. However, automated and online microbiological sensors have been emerging for several years now. They include the Biotrack, which can specifically monitor Aeromonas bacteria. Aeromonas is the legal parameter for regrowth in the drinking-water distribution network and it exceeds the legal standard in several distribution areas.


The Biotrack, an online sensor, can detect Aeromonas bacteria quickly and specifically. This method is based on staining the DNA to determine numbers of bacteria. Further development of the underlying software could, in principle, provide information about the form in which these bacteria occur in the water. The goal of the project was to further develop the detection of Aeromonas etermination by the Biotrack, test it, and study its practical applicability for drinking water companies. An additional aim was to see what information the Biotrack provides, and how that information can be used to understand and tackle the regrowth process in the distribution network better.

The fast online sensor Biotrack that allows the detecttion of specific bacteria within hours.


Given the impact of the corona measures on Biotrack, it was decided in joint consultation with all partners to terminate the project early. Despite the early termination of the project, a number of experiments were conducted and they are summarised in brief below.

Results from the Biotrack in the range of 100 to 100,000 Aeromonas bacteria would appear to be similar to those with the conventional culture method (the current analysis required by law). Tests with a small set of Aeromonas and non-Aeromonas bacteria showed that several strains of Aeromonas bacteria are detected, but that other bacterial strains are not. In exploratory measurements of different types of water (drinking water and discharge water), the results for drinking water samples with the Biotrack were good. However, for reliable measurements of discharge water, the Biotrack requires optimisation since the particles present in discharge water affect the measurement.


A good online sensor for Aeromonas has the potential to generate a lot of information for drinking water companies about the presence of Aeromonas in drinking water, allowing for a better understanding of the dynamics in the distribution network. In addition, a clearer picture has been obtained of how the sensor can best be used by potential customers and also marketed in the Netherlands and elsewhere.

Colonies of Aeromonas bacteria grown on a specific medium.